import re

# xxxx@xx.xx.xx


my_email = 'jinsheng_work@163.org.net'
match = re.match(r'[0-9a-zA-Z._]{1,20}@[\w]{2,10}\.[\w]{3,5}(\.[a-z]{2,3})?', my_email)
if match:
    print('yes')
else:
    print('no')